1. Field of the Invention
The present invention relates to pulse signal generators.
2. Description of the Related Art
Pulse signal generators responsive to the position or speed of a moving object or a variety of operations have been used in the fields of automatic controls, and electrical and electronics equipment.
An example of the pulse signal generators of this type is a rotation detector that employs an electromagnetic, light pick-up, or Hole or magnetic reluctance element. The electromagnetic type, however, suffers from a low output at low speed rotations. The light pick-up type requires a broadband d-c amplifier and a dust-proof structure. The Hole or magnetic reluctance type requires a plurality of elements and an amplifier. Some elements of the light pick-up/Hole/magnetic reluctance type are too sensitive to temperatures to be used in the atmosphere that can have a large temperature change. Consequently, where the rotation detector is used to detect the rotary speed or position of a crank or cam shaft of a car, it is impossible to detect very low to high speed rotations.
Japanese patent application Kokai No. 2000-101401 discloses a pulse signal generator that employs a magnetic element wire capable of producing large Barkhausen jumps to detect very low to high speed rotations. The pulse signal generator is able to resolve the above-mentioned problems but needs further improvements for use in automobiles, etc.
For example, in order to increase the change of a magnetic field applied to the magnetic element wire under set and reset conditions, an adjusting yoke is attached to the rear face of the magnet, the length of the magnetic element wire is reduced below a half of the length of the magnet and yoke combined, the magnetic fields by a pair of magnets are made different by changing the power, volume, or shape of the magnets, the position of the magnetic element wire is changed relative to the magnets, or the magnets are tilted relative to each other.
Also, it is necessary to reduce the manufacturing cost and size of a unit, the time for assembly and adjustment, variations in the product quality, and the product yield. Furthermore, there is a demand for a pulse signal generator capable of generating a pulse signal with high resolution to effect fine control of angles of a rotary object. The pulse signal generator of JP 2000-101401, however, fails to meet these requirements.
Accordingly, it is an object of the invention to provide a pulse signal generator capable of meeting such requirements as described above.
According to the invention there is provided a pulse signal generator comprising a plurality of magnetic elements arranged in an imaginable plane and capable of producing large Barkhausen jumps; a first unit for generating a magnetic field, which is changed by the object to be detected to cause said magnetic elements to produce said large Barkhausen jumps, said first unit consisting of a pair of magnet/yoke combinations provided on opposite sides of said imaginable plane such that their poles are oriented in opposite directions, forming a detecting area at an end thereof; a second unit for detecting said large Barkhausen jumps to produce corresponding pulse signals; and first and second adjusting yokes being movable on one of said magnet/yoke combinations along one of said magnetic elements and on the other of said magnet/yoke combinations along the other of said magnetic elements, respectively.
According to an embodiment of the invention, said magnetic elements are neither longer than said magnet/yoke combinations nor shorter than a half said magnet/yoke combinations.
According to another embodiment of the invention, one of said magnetic elements is arranged closer to one of said magnet/yoke combinations while the other of said magnetic elements is arranged closer to the other of said magnet/yoke combinations than said one of said magnet/yoke combinations.
According to still another embodiment of the invention, each of said magnet/yoke combinations is composed of a pair of magnet/yoke sub-combinations bonded together on the sides such that each of said magnetic elements and each of said adjusting yokes are arranged so as to correspond to one of said sub-combinations.
According to yet another embodiment of the invention there is provided a pulse signal generator system comprising a plurality of said pulse signal generators such that they are offset in a direction of motion of said object.